Conveyor systems are routinely used to handle and transport products both within confined physical spaces and between upstream and downstream destinations located in remote sections of a facility. Such systems which move products, especially heavy products, over long distances, are subject to excessive load forces during the transport process. In addition, product accumulation systems, which are routinely used in conjunction with conveyors for the storage and accumulation of product, employ conveyors and conveyor systems which, given the amount of product which is carried and may be accumulated, are also subject to excessive weight from the loads being transported.
In the normal handling process, systems employing long product conveying surfaces and product accumulators, experience substantial loads even during normal operations. When the products being handled are heavy to begin with, additional excessive forces are experienced by the conveyor surface. It is of critical importance to assure that the working strength of the conveyor and its conveyor chain or similar components are not exceeded during operation of the systems.
Prior solutions for handling excessive loads and accumulating product routinely employ very long conveyor pathways with multiple drives, spaced at designated locations, to distribute the load and ensure continued movement of the conveyor system without exceeding the working strength of the conveyor belt components. Other prior systems contemplate the use of multiple conveyors with multiple drives, forming lengthy pathways for movement and accumulation of product.
Multi-drive systems routinely use conveyors formed of chain circuit components. The chain on the conveyor comprises the carrying surface on which the product being transported moves from point of origin to point of destination. However, there are physical limits to the chain""s ability to move loads substantial distances and to accumulate heavy loads. If the load on a given chain exceeds the design limit of the chain, that chain and the conveyor will fail prematurely. As a result, action must be taken to reduce the amount of load that the chain, in its given application, must withstand. As an example, if a conveyor needs to move a product 100 feet and the acceptable load for a given chain conveyor dictates that the maximum length can only be 70 feet, then the conveyor must be split and two drives installed, basically changing the system from a one conveyor to a two conveyor system, with each conveyor being able to convey its particular load within the design limits of the conveyor chain component.
Such a conveyor system normally consists of a frame which supports the conveyor chain, such that its upper or product carrying surface moves along a designated path. The frame also provides a path for the chain to return, by traveling underneath the frame and up to the carrying surface once again.
At the tail end or infeed end of the conveyor, a shaft and bearings, which support sprockets, acts as a transition section from the return path to the carrying surface of the conveyor. This is a free turning sprocket, shaft, and bearing assembly, to which no power is applied. The movement of the chain from the return path to the product carry surface is what causes the sprockets to turn.
At the drive or discharge end of the conveyor, there is a drive sprocket assembly, with bearing support shaft, that is mechanically connected to the power transmission source. This source imparts power to the drive assembly, turning the sprockets, thereby pulling the chain across the length of the frame of the conveyor. As the chain leaves the drive sprocket assembly, there is no load on any particular link of chain which is disengaged from the sprocket. The first point of load development occurs when the chain feeds back into the return path and starts to slide through the path. The amount of load that is developed is a function of the weight of the chain, the length of the chain, the friction coefficient between the chain and the return path material, and the degrees of curve that the chain must pull through on the return path.
When the chain completes its path through the return track and wraps around the tail end sprocket, it begins its path as the product or load carrying surface. The amount of load on the carry side is a function of the chain length, the chain weight, the coefficient of friction between the chain and the carry track, the product weight, the number of products on the conveyor, the coefficient of friction between the product and the chain, the amount of slippage that will occur between the product and the chain in the event that products back up on the conveyor, and the number of curves that the carry surface must go through to get to the downstream destination.
The load is calculated in a sequential build-up, starting at the drive, through the return, and then through the carry surface, until it engages the first tooth of the sprocket. The entire load of the conveyor has to be pulled by the tooth of the sprocket that is engaging the first link of the chain to become engaged by the drive sprocket. This is what determines the working strength of the chain. The materials of construction of the chain and the sprocket is what determines the working strength of the combination.
As previously described, in order to ensure that the working strength of the conveyor systems are not exceeded by the loads being conveyed, multiple power drives are routinely used to distribute the load in a continuous path conveyor or conveyors are split and driven by multiple power means to ensure that the design limitations are not exceeded. However, such prior systems disadvantageously require a substantial amount of physical space and so are not easily and efficiently manufactured and assembled. Such systems also require extra components, including conveyor chain, frame, and connecting components, especially for the substantial return paths which are required. Maintenance, cleaning, and sanitization is also difficult with such large systems.
It is thus the object the present invention to overcome the limitations and disadvantages of prior product conveying and accumulation systems.
It is an object of the present invention to provide a conveying system which uses a carousel conveyor path arrangement to efficiently and effectively transport and accumulate excessive loads.
It is a further object of the present invention to provide a product conveyor system which employs a single continuous loop path that runs through multiple power drives, in order to distribute product load.
It is another object of the present invention to provide a product conveyor system which efficiently and effectively carries substantial loads without exceeding the working strength of conveyor components.
It is still another object of the present invention to provide a product conveyor system which eliminates substantial components of the return sections of the conveyor system and generally reduces the size of the overall system.
It is another object of the present invention to provide a product conveyor system which generally uses less components and thus is less costly to manufacture and assemble.
It is a further object of the present invention to provide a product conveyor system which can be constructed in a relatively small physical space.
It is still a further object of the present invention to provide a product conveyor system which allows for ease of maintenance, cleaning, and sanitization.
It is another object of the present invention to provide a product conveyor system which operates relatively quietly while transporting product.
It is a further object of the present invention to provide a product conveyor system which efficiently and effectively places multiple power drives, thereby overcoming overload problems associated with the conveying and accumulation of products of excessive weight.
It is still another object of the present invention to provide a product conveyor system which comprises multiple power drives which are automatically synchronize and balance each other during product transport, even during unbalanced load conditions.
These and other objects of the invention are accomplished by the present invention which consists of a conveyor system comprising of a continuous path conveyor. The conveyor may be formed of a continuous loop of chain elements. The conveyor path consists of two or more product carrying sections and corresponding offset return path sections. A product carrying section of the conveyor wraps around power driven sprockets where it is fed into and becomes a return path section. From there the path is guided over and aligned with free turning tail sprockets, where it is returned as a product carrying section. This section is then fed onto second drive sprockets, powered by another power means, where it again becomes a return path section, guided over tail sprockets and returned as a product carrying section. In this manner, the load of the conveyor chain is relieved at each drive sprocket assembly, thereby increasing the available working distance of the system.
Novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention, itself, however, both as to its design, construction and use, together with the additional features and advantages thereof, are best understood upon review of the following detailed description with reference to the accompanying drawings.